Semiconductor module having a plurality of heat sink plates

This application is based on Japanese Patent Application No. 2021-036074 filed on Mar. 8, 2021, the disclosure of which is incorporated herein by reference.

The present disclosure relates to a semiconductor module.

A semiconductor module may include a substrate and a semiconductor element located inside a substrate.

The present disclosure describes a semiconductor module including a substrate, a semiconductor element and a heat sink plate.

A semiconductor element included in a semiconductor module may be a power semiconductor element, and may generate a large amount of heat along with an electrical conduction.

In the structure in which a semiconductor element, in particular, a power semiconductor element is arranged in a substrate of a semiconductor device, it may be difficult to dissipate the heat generated by the semiconductor element to outside so that an excessive increase in the temperature of the semiconductor element may occur.

According to an aspect of the present disclosure, a semiconductor module includes a substrate, a semiconductor element and a heat sink plate. The substrate is included in a circuit board. The semiconductor element is disposed at the heat sink plate inside the substrate. A fluid is sealed inside the heat sink plate.

By adopting a structure in which the fluid is sealed inside the heat sink plate, for example, it is possible to enhance the thermal conduction of the heat sink plate and to provide anisotropy to the thermal conduction of the heat sink plate. As a result, it is possible to diffuse the heat generated by the semiconductor element in a wider range of the substrate through the heat sink plate, and it is possible to effectively suppress an increase in the temperature of the semiconductor element.

In a semiconductor module according to the following embodiment of the present description, the thermal conductivity of a heat sink plate may have anisotropy in a plan view. According to such a structure, it is possible to effectively diffuse the heat generated by a semiconductor element according to the shape of the heat sink plate or the shape of a substrate.

In the following embodiment of the present description, the heat sink plate may have a rectangular outer shape. In this situation, the thermal conductivity in the longitudinal direction of the heat sink plate may be higher than the thermal conductivity in the lateral direction of the heat sink plate. According to such a structure, it is possible to evenly diffuse the heat generated by the semiconductor element over the tire heat sink plate.

In the following embodiment of the present description, it is possible to further include multiple terminals that are exposed to the surface of the substrate and electrically connected to the semiconductor element. In this situation, the multiple terminals may be disposed to face the heat sink plate in the lateral direction of the heat sink plate. According to such a structure, it is possible to shorten the current path connecting the multiple terminals and the semiconductor element to reduce the impedance of the current path. As the impedance of the current path is reduced, the heat generation in the current path is suppressed so that the temperature rise in the semiconductor element is also suppressed.

In the following embodiment of the present description, the heat sink plate may be a heat pipe or a vapor chamber. The heat pipe and the vapor chamber are examples of the heat transfer member in which the fluid is enclosed, and such a heat transfer member can be suitably adopted for the heat sink plate described in the present description.

In the following embodiment of the present description, the heat sink plate may be made of metal or graphite. The metal and graphite are materials having excellent thermal conductivity, and such heat transfer members can be suitably adopted for the heat sink plate described in the present description.

In the following embodiment of the present description, a semiconductor module may further include a control circuit that controls the operation of the semiconductor element. According to such a structure, it is possible to suppress the temperature rise in the semiconductor element. Therefore, it is possible to avoid a situation in which the control circuit is overheated, when the control circuit is disposed at the surface of the substrate.

According to another aspect of the present description, it is possible to reduce the impedance of the current path in the semiconductor module having a built-in semiconductor element. In the following embodiment of the present description, the semiconductor module may include a substrate, a semiconductor element, a heat sink plate, and multiple terminals. The semiconductor element is disposed in the substrate. The heat sink plate is provided with the semiconductor element inside the substrate. The multiple terminals are exposed to the surface of the substrate, and are electrically connected to the semiconductor element inside the substrate.

In the following embodiment of the present description, the heat sink plate may have a rectangular outer shape. In this situation, the multiple terminals may be disposed in the lateral direction of the heat sink plate with respect to the heat sink plate. According to such a structure, it is possible to shorten the current path connecting the multiple terminals and the semiconductor element to reduce the impedance of the current path.

In the following embodiment, at least one of the multiple terminals is located at one side of the heat sink plate to face the heat sink plate in the lateral direction, and at least another one of the multiple terminals is located at the other side of the heat sink plate to face the heat sink plate in the lateral direction of the heat sink plate. According to such a structure, it is possible to effectively shorten the current path connecting the multiple terminals and the semiconductor element to further reduce the impedance of the current path.

The following describes a semiconductor moduleaccording to the embodiment with reference to the drawings. The semiconductor moduleaccording to the present embodiment is adopted, for example, in a power control unit in an electric vehicle, and can convert power between a power supply and a drive motor. The electric vehicle in the present embodiment broadly means a vehicle having a motor for driving wheels, and for example, an electric vehicle charged by an external electric power, a hybrid vehicle having an engine in addition to the motor, a fuel cell vehicle having a fuel cell as the power source and the like. However, the application of the semiconductor moduleaccording to the present embodiment may not be limited to the electric vehicle, and may be applied to a variety of electrical apparatuses.

As illustrated in, the semiconductor moduleincludes a substrate, multiple semiconductor elementstoand multiple heat sink platesto. The substratemay also be referred to as a substrate main body or a substrate body. The substratehas a boarded shape or a plate-like shape. The substratehas an upper surfaceand a lower surface. The lower surfaceis located at a side opposite to the upper surface. The substrateis made of an insulator, for example, an epoxy resin or other resin material.

X-direction and Y-direction in the drawings are directions parallel to the upper surfaceand the lower surfaceof the substrate, and are directions perpendicular to each other. Z-direction is a direction perpendicular to the upper surfaceand the lower surfaceof the substrate, and is a direction perpendicular to each of the X-direction and the Y-direction.

Semiconductor elementstoare located inside the substrate, and are sealed by the substrate. Each of the semiconductor elementsandis a power semiconductor element, and in particular, a switching element. This switching element may be, for example, an Insulated Gate Bipolar Transistor (IGBT) or a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). The semiconductor elementstorespectively have upper surface electrodestoand lower surface electrodesto, and respectively conduct electricity or block an electrical conduction between the corresponding upper surface electrodestoand the corresponding lower surface electrodesto

As an example, in the semiconductor modulein the present embodiment, the multiple semiconductor elementstoare respectively referred to as a first semiconductor element, a second semiconductor element, a third semiconductor element, a fourth semiconductor element, a fifth semiconductor elementand a sixth semiconductor element. The first semiconductor elementand the second semiconductor elementare electrically connected in series inside the substrate. The third semiconductor elementand the fourth semiconductor elementare electrically connected in series inside the substrate. The fifth semiconductor elementand the sixth semiconductor elementare electrically connected in series inside the substrate.

Heat sink platestoare located inside the substrate, and are sealed by the substrate. Each of the heat sink platestoincludes a boarded shape ora plate-like shape, and is arranged on the same plane parallel to the substrate. In other words, each of the heat sink platestois perpendicular to the Z-direction. Each of the heat sink platestoincludes a conductor such as copper, a metal other than copper, or graphite. The structure of each of the heat sink platestois described in the following.

As an example, the heat sink platestoin the semiconductor moduleaccording to the present embodiment are respectively referred to as a first heat sink plate, a second heat sink plate, a third heat sink plate, a fourth heat sink plate, a fifth heat sink plate and a sixth sink plate. The first heat sink plateand the second heat sink plateare aligned along the X-direction. The third heat sink plateand the fourth heat sink plateare aligned along the X-direction. The fifth heat sink plateand the sixth heat sink plateare aligned along the X-direction. The first heat sink plate, the third heat sink plateand the fifth heat sink plateare aligned along the Y-direction. The second heat sink plate, the fourth heat sink plateand the sixth heat sink plateare aligned along the Y-direction.

The first semiconductor elementis arranged at the first heat sink plate, and the lower surface electrodeof the first semiconductor elementis electrically connected to the first heat sink plate. The second semiconductor elementto the sixth semiconductor elementsare respectively disposed at the second heat sink plateto the sixth heat sink plate. The lower surface electrodestorespectively included in the second semiconductor elementto the sixth semiconductor elementare correspondingly electrically connected to the second heat sink plateto the sixth heat sink plate.

The semiconductor moduleincludes terminals,,,,. These terminals,,,,are external connection terminals for connecting to an external circuit. The terminals,,,,are made of a conductor such as copper or other metal. As an example, the terminals,,,,are respectively referred to as a P terminal, an N terminal, a U terminal, a V terminaland a W terminal. The P terminaland the N terminalare located to face one side of each of the heat sink platestoin the X direction. The U terminal, the V terminaland the W terminalare located to face the other side of each of the heat sink platestoin the X direction. The terminals,,,,are disposed at the lower surfaceof the substrate. However, one or more of the terminals,,,,may be disposed at the upper surfaceof the substrate.

The P terminalis electrically connected to the first heat sink plate, the third heat sink plateand the fifth heat sink plateinside the substrate. As a result, the P terminalis electrically connected to the respective lower surface electrodes,,of the first semiconductor element, the third semiconductor elementand the fifth semiconductor elementthrough one of the heat sink plates,,. The N terminalis electrically connected to the respective upper surface electrodes,,of the second semiconductor element, the fourth semiconductor elementand the sixth semiconductor elementinside the substrate.

The U terminalis electrically connected to the upper surface electrodeof the first semiconductor elementinside the substrate. The U terminalis electrically connected to the second heat sink plate, and is electrically connected to the lower surface electrodeof the second semiconductor elementthrough the second heat sink plate. The V terminalis electrically connected to the upper surface electrodeof the third semiconductor elementand the fourth heat sink plate, and is electrically connected to the lower surface electrodeof the fourth semiconductor elementthrough the fourth heat sink plate. The W terminalis electrically connected to the upper surface electrodeof the fifth semiconductor elementand the sixth heat sink plate, and is electrically connected to the lower surface electrodeof the sixth semiconductor elementthrough the sixth heat sink plate.

The semiconductor modulein the present embodiment is arranged between a direct current (DC) circuit and a three-phase alternating current (AC) circuit, and can function as a three-phase inverter circuit. In this situation, the P terminaland the N terminalare connected to the DC circuit, and the U terminal, the V terminaland the W terminalare connected to the three-phase AC circuit. As the semiconductor elementstoare selectively turned on and turned off, each of the U terminal, the V terminaland the W terminalis electrically connected to either the P terminalor the N terminal. As a result, the semiconductor moduleconverts DC power from the DC circuit into AC power and supplies the AC power to the three-phase AC circuit, or converts the AC power from the three-phase AC circuit into the DC power and supplies the DC power to the DC circuit. As described above, the semiconductor modulein the present embodiment may be adopted, for example, in an electric vehicle. In this situation, the semiconductor moduleis arranged between a power supply device as the DC circuit and the drive motor as the three-phase AC circuit, and executes power conversion between the power supply device and the drive motor.

The semiconductor modulefurther includes a control circuit. The control circuitis disposed at the upper surfaceof the substrate. The control circuitincludes multiple surface electrical components. The surface electric componentsinclude, for example, a gate drive circuit that controls switching of the semiconductor elementsto. As described above, the semiconductor modulein the present embodiment includes a structure in which the semiconductor elementstoand the heat sink platestoare incorporated in a circuit board having the control circuit. The number of the semiconductor elementstoand the number of the heat sink platestoare not particularly limited. The semiconductor modulemay include at least one semiconductor element and at least one heat sink plate. In this case, the semiconductor element is not limited to the switching element, and may be another type of semiconductor element such as a diode.

The following describes the heat sink platestowith reference to. The heat sink platestoin the present embodiment respectively have identical structures. Therefore, each ofillustrates only the first heat sink plate, and omits the illustration of other heat sink platesto. However, some or all of the heat sink platestomay have different structures.

As illustrated in, the heat sink platestorespectively have rectangular outer shapes. The longitudinal direction of each of the heat sink platestois parallel to the Y-direction, and the lateral direction of each of the heat sink platestois parallel to the X-direction. In the semiconductor module according to the present embodiment, the terminals,,,,are arranged to face the heat sink platestoin the X-direction. In other words, the terminals,,,,are disposed to face the heat sink platestoin the lateral direction of the heat sink platesto. According to such a structure, it is possible to enlarge the size of each of the heat sink platestowhile shortening the distance between each of the terminals,,,,and each of the heat sink platesto.

As the size of each of the heat sink platestoincreases, the heat generated by the semiconductor elementstois diffused over a wider range in the substrate. As a result, the temperature rise in the semiconductor elementstois effectively suppressed. As the distance between each of the terminals,,,,and each of the heat sink platestodecreases, it is possible to shorten the current path through which the current flows in the substrate, and it is possible to reduce the impedance in the current path. By enlarging each of the heat sink platestoso as to have a rectangular shape in one direction and disposing the terminals,,,,in the lateral direction of the rectangular shape, it is possible to enhance the cooling performance and reduce the impedance.

As illustrated in, multiple roomsare formed inside the heat sinkin a cross sectional view of the heat sink platetaken along the line VB-VB in, and a fluidis sealed inside each of the roomsin a cross sectional view of the heat sink platetaken along the line VB-VB in. The fluidis heated and vaporized in a high temperature part of each of the heat sink platesto. The fluidcondenses and liquefies in a low temperature portion of each of the heat sink platesto. By repeating the above described cycle, the convection of the fluidis formed in the room, and the thermal conduction in each of the heat sink platestois enhanced. As a result, the heat generated in each of the semiconductor elementstois diffused over a wider range in the substrate, and the temperature rise in each of the semiconductor elementstois effectively suppressed.

Although not particularly limited, each of the heat sink platestoin the present embodiment has a so-called heat pipe structure. Each of the roomsinside the heat sink platestoextends in a pipe shape, and the fluidin each of the roomsconvects along a longitudinal direction of the pipe shape. In other words, the fluidconvects along the longitudinal direction (Y direction) of each of the heat sink platesto. Each of the roomshaving a pipe shape extends along the longitudinal direction of each of the heat sink platesto. Therefore, the thermal conductivity of each of the heat sink platestohas anisotropy in a plan view. The thermal conductivity in the longitudinal direction or a longer side of each of the heat sink platestois higher than the thermal conductivity in the lateral direction or a shorter side of each of the heat sink platesto. According to such a structure, in each of the rectangular heat sink plateto, it is possible to evenly diffuse the heat generated by each of the semiconductor elementstoto each of the entire heat sink platesto.

Each ofillustrates a heat sink plateaccording to a first modification. The heat sink platemay be adopted for any of the first heat sink plateto the sixth heat sink platein the semiconductor module. The heat sink plateaccording to the first modification has a so-called heat spreader structure, as illustrated in. Therefore, as illustrated in, a roomis formed inside the heat sink platein a cross sectional view of the heat sink platetaken along the line VIB-VIB in, and the fluidis sealed inside the roomin a cross sectional view of the heat sink platetaken along the line VIB-VIB in. Even with such a structure, it is possible to provide anisotropy to the thermal conductivity of the heat sink plate. In this situation, the thermal conductivity in the longitudinal direction or a longer side of each of the heat sink platestois higher than the thermal conductivity in the lateral direction or a shorter side of each of the heat sink platesto.

Each ofillustrates a heat sink plateaccording to a second modification. The heat sink platemay be adopted for any of the first heat sink plateto the sixth heat sink platein the above described semiconductor module. As illustrated in, the heat sink plateaccording to the second modification includes a solid structure made of a conductor such as copper, a metal other than copper, or graphite in a cross sectional view of the heat sink platetaken along the line VIIB-VIIB in. In other words, the fluid is not sealed inside the heat sink plateaccording to the second modification. As described above, in the semiconductor moduleaccording to the present embodiment, each of the heat sink platestohas a rectangular outer shape. It is possible to enhance the cooling performance and reduce the impedance by respectively disposing the terminals,,,,in the lateral direction of the heat sink platesto. However, even if the heat sink plateillustrated inis adopted, the identical advantageous effect can be attained.

In the semiconductor moduleaccording to the present embodiment, single semiconductor elementstoare respectively disposed at the corresponding heat sink platesto. On the other hand, as illustrated in, multiple first semiconductor elementsare disposed at the first heat sink plate. In this case, multiple first semiconductor elementsmay be arranged along the longitudinal direction of each of the heat sink platesto. With such an arrangement, it is possible to suppress the difference in the current paths generated among the multiple first semiconductor elements, and it is possible to achieve the uniformness of the currents respectively flowing through the multiple semiconductor elements. Similarly, the multiple semiconductor elementstomay also be arranged at the other heat sink platesto.

Although specific examples of the techniques disclosed in the present description have been described in detail above, these are merely examples and do not limit the scope of the present description. The techniques described in the present description include various modifications and modifications of the specific examples illustrated above. The technical elements described in the present description or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the present description at the time of filing. The techniques illustrated in the present description or drawings can achieve multiple objectives at the same time, and achieving one of the objectives itself has technical usefulness.